In order for my client to choose whether or not a layer can be scrolled (and
still be able to edit text outside the visible area if it does scroll), I've
created an editable Template Parameter :

<!-- InstanceParam name="Scroll" type="boolean" value="true" -->

This parameter is then used to determine the width of a higher layer - 'mask'.
If Scroll=false the layer is wider, and should cover the scroll buttons,
rendering them useless. If Scroll=true the layer is narrower, and buttons
should be visible.:

<td width="263" height="20" colspan="2">
<div id="mask" style="position:absolute; background-color:#FFFFFF;
width:@@(Scroll=true?'240':'263')@@; height:60; z-index:2; top:300; left:247;
visibility:visible; overflow:hidden;">
</div>
</td>

This seems to work only when I save the template and templated pages are
updated. When I go into a page to change the value of Scroll from true to
false for example, the width of the 'mask' layer remains at true, even though
I can see in the page source that it has been changed to false.

Needless to say, this is driving me up the proverbial wall - please help!